meaning of draft

[ssa1]

hello, is there any one who can explain the meaning of + DFT and - DFT after the dimensions in the drawing. what it implies? thank you

 

[dgs]

It means that that dimension is the nominal dimension and the draft on the part makes itlarger and smaller, respectively.


For example, the rib is .09 thick at the top and gets thicker as you transition to the bottom, based on the draft angle.

 

[design-engine]

to boot... make sure you keep the 70 percent rule on the base of your ribs. i.e. 70 percent of the material thickness. Another suggestion I give in plastics workshops is to use a parameter for the material thickness (shell) so your nominal rib thickness is always 69 percent of the shell thickness.

In most cases where a sink mark occurs is where 12 of 13 ribs were modified after changing the shell thickness. the 13th rib gives and unflattering sing mark.